bugfix removing multiple fieldsets does't work

[svycka]

at the same time iterating collection items and removing causes problem:
When we have 3 items but we delete second and third. It fails and does not remove third element. So we have to move remove out of foreach

[svycka]

fixes #7443

[Maks3w]

Please add a unit test

[Maks3w]

So the issue is modify and read the iterator (PriorityList) in the same loop.

Should this to be fixed in PriorityList instead?

[svycka]

@Maks3w I don't think this should be allowed in PriorityList. Also don't see how this could be implemented.

foreach PriorityList
    remove
    remove
endforeach
PriorityList->commit

does not feel right

[svycka]

@Maks3w if you don't like how it is fixed I could change:

foreach ($this->iterator as $name => $elementOrFieldset) {
// to
foreach ($this->iterator->getIterator() as $name => $elementOrFieldset) {

this would also fix the issue.

[Maks3w]

I delegate to other @zendframework/community-review-team member for their opinions.

To have a temportal $removed array is weird for me

[svycka]

I have found commit witch introduced the bug
PR: #6240
commit: 9a5dd60#diff-31fe6580a729ea0519189ac9ef45928aL212

[weierophinney]

Why not just remove as we discover valid names?

[weierophinney]

Interestingly, because doing so causes unexpected behavior.

[Maks3w]

IMO this should be fixed in PriorityList instead

[weierophinney]

I've tried a few different approaches at this time. The problem is that doing removal while inside the loop leads to inconsistent results; the underlying iterator is not updated in place correctly. As such, the first pass is to determine which we can remove, and then we remove each.